Quick connect couplings are used, for example, to connect hoses in hydraulic fluid lines. A typical application is on agricultural tractors to connect the tractor hydraulic system with attachable implements. The tractor typically includes one or more female coupler sockets, while the implements include one or more male coupler nipples.
Over the years changes have occurred in these systems which have required changes and performance improvements in the couplings. It is typically desirable for these couplings to connect regardless of trapped pressures within either the male or female side. It is also typically desirable for these couplings to connect without excessive leakage of fluid during attachment or detachment.
One known coupling design that attempts to address such issues is WO 2015/067794, which discloses a non-spill female coupler of a flat face design having an inner assembly axially sliding inside an outer assembly, and a seal adapted to generate a pressure difference between an incoming supply line and a chamber at the rear of the inner assembly. The seal includes a deformable portion and a non-deformable portion, and is adapted to open and close a communication pipe between the supply line and the rear chamber so as to introduce pressure to the rear chamber, but prevent flow in the reverse direction from the rear chamber toward the supply line. However, preventing reverse flow in this way can cause problems when the fluid in the rear chamber is trapped and pressure of this trapped fluid increases due to temperature or other factors. For example, the pressure trapped in the rear chamber may increase excessively due to such factors, and without a user manually relieving the pressure in the rear chamber to a rear drain line, there is no other mechanism to relieve such pressure, which may lead to catastrophic failure of the coupler.
The known coupler referenced above also includes a rigidly mounted locking member that is fixed to the valve body, such that the entire valve body must shift a sufficient distance for the locking elements to lock into place during connection with the male coupler. However, such a configuration causes problems of increased connection force because it requires the user to exert enough force to overcome a centering spring and move the entire valve body far enough that the locking elements can lock into place. The configuration of the known coupler may also have problems with a non-connect range in which the interface pressure at the coupling is higher than the centering spring force, which may prevent the coupling from being able to lock.